The present invention relates to light-stable structures, specifically structures comprising a polymeric film and an ultraviolet light-absorbing compound that inhibits degradation of the film despite exposure to ultraviolet light in an inert environment.
A vast number of polymeric films are available for use in a wide variety of applications. For example, polymeric films may be used as decorative or protective layers. Use of some polymeric films can be severely limited for outdoor applications and other applications where the films are exposed to a source of light. For example, many polymeric films degrade when subjected to prolonged exposure to ultraviolet (UV) radiation (i.e., wavelengths less than about 400 nanometers (nm), e.g., wavelengths between about 200 and 400 nm, e.g. wavelengths between about 315 and 400 nm). Exposure to UV radiation occurs naturally during use outdoors or during exposure to fluorescent light or other UV-emitting light sources.
Polymeric films that have undergone UV degradation may show detrimental changes in color and/or mechanical properties. Color-fast films resist color degradation. Certain films are known to have inherent color-fastness in the presence of UV light. Other polymeric films do not exhibit color-fastness, for example, clear films containing an aromatic moiety (e.g., some polyesters) may yellow when exposed to UV light. These non-color-fast films may require the addition of a modifier such as a UV stabilizer. The modifier may be incorporated directly into the polymeric film, it may be present in a coating applied to one or both surfaces of the film, or it may be part of a layer positioned between the source of the ultraviolet light and the polymeric film.
Briefly, in one aspect, the present invention provides an assembly comprising an inert environment bounded on at least one side by a pane, wherein the pane is at least partially transparent to ultraviolet light, a structure positioned in the inert environment, the structure comprising a polymeric film and an effective amount of a ultraviolet light-absorbing compound, wherein the ultraviolet light absorbing compound comprises a triazine.
In another aspect, the present invention provides an assembly comprising an inert environment bounded on at least one side by a pane, wherein the pane is at least partially transparent to ultraviolet light, a structure positioned in the inert environment, the structure comprising a polymeric film, a resin layer and an effective amount of a ultraviolet light-absorbing compound, wherein the ultraviolet light absorbing compound comprises a triazine.
In yet another aspect, the present invention provides an assembly comprising an inert environment bounded on at least one side by a pane, wherein the pane is at least partially transparent to ultraviolet light, a structure positioned in the inert environment, the structure comprising a polymeric film, a layer comprising a first smooth surface and second structured surface being formed of a plurality of spaced parallel grooves, each said groove being formed by a first facet which is substantially perpendicular to the first smooth surface and a second facet which makes an angle between 1 to 60 degrees with the first smooth surface, and an effective amount of a ultraviolet light-absorbing compound, wherein the ultraviolet light-absorbing compound comprises a triazine.
In yet another aspect, the present invention provides an assembly comprising an inert environment bounded on at least one side by a pane, wherein the pane is at least partially transparent to ultraviolet light, a structure positioned in the inert environment, the structure comprising a polymeric film and an effective amount of a ultraviolet light-absorbing compound, wherein the ultraviolet light absorbing compound comprises a triazine, wherein the structure exhibits a delta b* yellowing value of less than 9 after exposure to a radiant dose of 6000 kJ/m2 at 340 nm, according to ASTM G-155 test method, employing a repeating test cycle of 8 hours of light at 88xc2x0 C., black panel temperature, followed by 4 hours dark at 50xc2x0 C., wherein the delta b* value is based on D-65, 10 degree observer, specular included, reflectance measurements. The b* values are based on the CIELab colorspace.
In yet another aspect, the present invention provides an assembly comprising a first pane, a second pane, a frame, wherein the frame secures the first and second pane, an inert environment between the first and second panes, a polymeric film positioned in the inert environment, and an effective amount of a ultraviolet light-absorbing compound, wherein the ultraviolet light absorbing compound comprises a triazine.
The above summary of the present invention is not intended to describe each discussed embodiment of the present invention.